Casing perforator



H. c. YARBROUGH ZASZGS CASING PERI-GRATOR Filed Nov. 24, 1953 2 Sheets-Sheet l March 2s, 1939.

INVE NTOR HwoLo C. Yaneeousrl ATTORNEY MarchkZS, 1939. H. ci. YARBROUGH CAS ING PERFORATOR Filed Nov. 24, 1953 2 sheets-sheet 2 l v 7 /////w////////////////r PIERO- 47 INVENTOR HAQoLD C. YAngousf-f TTORNEY Patented Mar. 28, 1939 ,UNITED STATE' s PATENT OFFICE y vCASING,` PERFORATOR yHarold C. Yarbrough, Brea, Calif., assignorfby mesne assignments, to Baasli-,Ross Tool Company, a corporation of California Application November 24, 1933` Serial No. 699,547

9 claims, (o1. 10i-0.4)`

This invention has to do in a general way with where the perforations are to be made and the outer casing may be embedded in cement. It is necessary, therefore, that the perforator be contance through the cement into the oil-bearing sand. i

It is, therefore, a primary object of this invention to provide a perforator of the class described in which the blade or cutter is normally supported inthe body of the perforator so as to not interfere with the movement of the unit downwardly throughy the casing, and is', at the saine time, constructed and operated so as to obtain a maximum extension ofthe blade from the body during a perforating operation. y,

Inasmuch as the conventional casing vused in present day oil well operations is formed of high n gradesteel andinas a Substantial wall thickness, it is obvious that the perforation or' such casing becomes extremely diiiicult. Furthermore, it is a self-evident fact that it is much more di'icult to penetrate or pierce a casing or casings of this L.) nature than it is to penetrate the cement or formation which lies adjacent the outer casing. For this reason, it becomes a further object of this invention to provide a tool of the class described which is designed so that the blade receives its maximum power thrust or is operated so as to have maximum cutting or piercing efficiency dur- A ing such vtime as'it `is acting'on or breaking through the casing as distinguished'from the' action, in other perforators` with which I am ,7, familiar in which the blade-piercing motionof maximum cutting eiilciency is distributed throughout the entire pcrforating operation.

With this object in mind, the general construction of the tool contemplated by this invention 7') comprises an elongated body which has an inclined slot terminating at its lower end in a pocket.

A cutter is mounted in the slot for free sliding movement therein and the pocket and cutter are so constructed that the cutter is normally sup- 55 ported in the pocket in a completelyfretracted ystructed so that the blade orvcutter will pierce' both casings'vand 'will extend a substantial disposition. In the operation of a tool of this nature, f it will be understood that the mostv satisfactory source of power for driving the blade ofthe cutter through the casing and into vthe formation' y is obtained from a downward movement of the Y body relative to the cutter, such movement being effected either by suitable jars or by the weight' of the casing which supports the tool. I have discovered that the power derived from moving thev body rin the manner just described m can be utilized with the maximum emciency by y engaging the point of the blade with the casing at an angle such that it will bite into the casing and will not skid or slip, at the same time supporting f the back of the blade on a substantially iixed ful` 15 Crum about which the blade turns during th downward movement of the body. *y

In the ldevice contemplated by this invention,l the construction is such that the blade is rotated from aposition of maximum inclination, in which the line of thrust is a radius from the fulcrum to the point of'penetration, to a rposition of maximum extension, in which the line of thrust is subu stantially normal to the casing'and the formation, during the initial downward movement of the 2r body or during that period of time in which the blade is initially piercing the casing or casingsl as the case may be.

In the particular construction contemplated by this invention, I provide two fixed fulcrum points '30 about which the blade turns while it is piercing the rst and second casings respectively. After the cutter has rotated about the second fulcrum pointit assumes the angle of maximum extension l above referred to and fromr this point on it is held against further turning movement and is'pushed outward into the formation byvirtue of the engagement of the back of the cutter with the inclined slot.

It is a further object of this invention to proo vvide a tool of the class described with novel means l,

operable from the surface of the ground for swinging the cutter into an extended position Where the blade bites into the casing. v

It is a further feature of this invention that the blade is constructed so that it may be easily retracted from the perforation by an upward pull on the body.

The details in the construction oi a preferred form of my invention, together with other objects attending its production, will be best underf stood from the following description of the accompanying drawings which are chosen for illustrative purposes only, and in which- Fig, 1 is a sectional elevation showing a pref k55 ferred form of my invention suspended in a well with the cutter in a retracted position;

Fig. 2 is a fragmentary front elevation of the tool shown in Fig. 1;

Fig. 3 is a plan section of the tool contemplated by this invention taken in a plane represented by the line 3 3 of Fig. 1;

Fig. 4 is a plan section similar to Fig. 3 taken in a plane represented by the line 4-4 of Fig. 1;

Fig. 5 is a plan section similar to Fig. 3 taken on the plane represented by the line 5-5 `in Fig. 1;

Fig. 6 is a plan section similar to Fig. 3 taken on a plane represented by the line 5--6 o! Fig. 1;

Fig. 7 is a plan section of the tool shown in Fig. 1 taken on a plane represented by the line 1-1, and illustrating the details in the construction of a preferred form of mechanism which is used to initially extend the cutter from the body;

Fig.` 8 is an enlarged fragmentary sectional elevation showing the cutter as having been swung into a position for piercing the first casins:

ing the position which is assumed after the body has been moved downwardly from the position of Fig. 8 to a point at which the first casing has been penetrated and the point of the blade engages the second casing;

Fig. 10 is a sectional elevation similar to Figs. 8 and 9 showing the body as having been moved downwardly to a point at which the cutter has rotated about a second fulcrum to penetrate the `second casing and assume a position of maximum extension;

Fig. 11 is a sectional elevation with the tool shown in outside elevation illustrating the p0- sition which the cutter assumes after the tool has been advanced a substantial distance beyond the position shown in Fig. 10;

Fig. 12 is a perspective view illustrating a preferred form of cutter contemplated by this inventlon; and

Fig. 13 is a plan section taken on the line I3-I3 of Fig. 12.

More particularly describing the invention as herein illustrated, reference numerals II and I2 indicate what I mayterm the inner and outer casings in an oil well which extend into a formation indicated at I3.

Reference numeral I4 indicates a `perforator body which has a threaded tip I5 on its upper endfor connection to a string of tubing, a jar, or other suitable suspending means. The body I4 is provided with a slot I6 in what I may term its front portion. 'Ihe slot I6 has an upper section` I1 which lnclines rearwardly and downwardly from the top of the body` The upper portion I1 of the slot is provided with a pair of oppositely disposed guide ways I8 so that this portion of the slot is T-shaped in cross section as shown in Fig. 3.

The guide ways I8 terminate at their lower end in an enlarged pocket I9 which has the same width as the guide ways and is provided in its back portion with what I may term a first fulcrum point or cam face and a second fulcrurn point or cam face 2|. The purpose of these fulcrum points will be more fully described further in the specification.

'I'he region oi' the slot below the pocket I3 contains a wedge block 23 which is provided with an enlarged boss 24 threaded to receive the upper threaded end of a mandrel 25. 'I'he portion of Fig. 9 is an enlarged sectional elevation showi the slot which contains the wedge block 23 ls provided with a circular enlargement 2G which forms a guide for the boss 24.

Reference numeral 21 indicates a bearing block which is mounted in the bottom of the body by means of pins 28, and has a passage 29 therethrough through which the mandrel extends.

Reference numeral 3D indicates a cutter which is mounted for free sliding movement in the slot I5. The shape of this cutter is best illustrated in Fig. 12 where it is shown as comprising a body portion 3i having a forwardly extending blade 32 and provided with side anges 33 and 33 which in the form shown constitutes what I may term a bearing shoe which has a rounded heel 34. The body portion 3i of the cutter is made of a width only slightly less than the width of the slot I5, and the shoe formed by flanges 33 and 33 has a width which corresponds to the overall width of the slot in the region of the guide ways I8.

It will be observed that the length of the shoe or flanges 33 and 33' is substantially less than the overall length of the body so that when the cutter is mounted within the slot it will drop into the pocket I9 and will fall forward to the position shown in Fig. 1` where the upper end portion of the cutter body lies within the slot I5 and the shoe lies within the pocket.

It is an important point that the length of the cutter body is such that it does not at any time extend through the slot outside of the main body I4 of the perforator. This is clearly illustrated in Fig. 1. It is also important that the length of the blade be such that when the cutter drops into the pocket as shown, the blade is supported by the wedge block 23 in a fully retracted position.

The width of the blade as shown in Fig. 13 is preferably less than the width of the main body portion of the cutter and is tapered. This construction provides shoulders 35 on the cutter which may be engaged by the edges of the perforations made by the blade when the cutter is fully extended, `and since the blade is tapered this arrangement greatly facilitates the extraction of the blade following a perforating operation.

In manufacturing a device of this character, I propose to form the perforator body I4 from a single piece of metal, cutting the slots therein by means of suitable milling tools. The pocket and the guide faces being of the same width, are preferably formed in the same operation, and in forming the pocket in this method of manufacture it is necessary to operate through the front of the tool. This leaves an enlarged opening which is closed by means of dovetailed blocks 36 held in place by means of screws 36. These blocks also serve to provide a safeguard against the cutter dropping into an extended `position when it is in the pocket. It will be understood of course that other methods may be employed in the manufacture of this device. For example, the tool may be made in several pieces secured together with any suitable means, such as screws or welds.

Reference numeral 31 indicates a block provided across the upper end of the guide ways in the slot to limit the upward movement of the cutter in the body or, more sepcically, limit the downward movement of the body relative to the cutter when the latter is engaged by a pipe.

In addition to providing a support for the cutter when it is in its normal or retracted position.

the wedge block 23 is provided for the purpose of extending the cutter through the slot from the body to a point at which vthe end of the blade engages the casing. For the, purpose of actuating the wedge block to accomplish this operation, I

provide the mandrel 25 with a friction member` 40 adapted to be at all times `in frictional engage'- v ment with the interior of the casing and associated with means for optionally locking the same to the mandrel at an intermediate point.

4This friction member 40 is shown as vcomprising a pair of spaced plate membersl 4! and 42 which are slidably mounted on the mandrel and which support a plurality of leal' springs 43 secured to the plate members at their opposite ends.

Theupper plate member 4| is provided with a pair of aligned notches 44 and 44" which are adapted to passa pin 45 mounted in vthe mandrel' at an intermediate point.

Reference numerals 46 and blocks or bosses which are formed on the'top of the upper plate 4l for thevpurpose of limiting the rotation of the pin 45 relative to the upper plate when the mandrel has been lifted to a point at whichthe pin lies above the plate. Reference numeral 41 indicates a nut mounted on the lower end of the mandrel for thepurpose ofv retaining the friction member thereon;

In operation, the body i4 is mounted on the lower end of a tube, jar, or other suitable suspending means and lowered into the well to a point at which it is desired to form the lowermost perforation, During this loweringmovement, the friction member 40 is mounted on the mandrel so that the upper plate lies above the pin 45 as shown in Fig. l. When the desired point has been reached, the tool is raised a distance cor- Y responding substantially to the distance from the pin to the upper plate and the tool is rotated, such rotation being effective to bring the pin into alignment with the notches and 44.

Since the rotation is made with the suspending means under a slight tension, it will be seen that when theA pin comes into alignment with the notches, the unit will be drawn upwardly bringing the pin to a point above ythe upper plate, the

` rotation being continued brings the p-in 45 to the dotted line position shownl in Fig. 7 where it engages the bosses 46and 48. In this way, the mandrel is locked against downward movement relative to the friction member. The tool is again lowered, such movement beingeffective to move the body downward relative to the mandrel `which is being held in position by the friction This relative movement between the member. body and the mandrel vcauses the wedge block 23 to swing the cutter 30 into the position shown in Fig. 8, wherethe point of the blade engages the inner casing I l. This position is what I may term a position design oi the toolis such that the angle A which the line of thrust L makes with the casing Il is in the neighborhood of 65 which I nd to be the most efficient angle for cutting the pipe and at the same time avoiding a skidding or slipping action, of the blade against the pipe.;

After the cutter body is i dropped or forced downwardly from theV position shown in Fig. 8,

the'blade is held in compression along the line L so as to swing or lrotate about the first fulcrum point or cam face 20. During this rotation, ther blade is forced through the first casing lll, and,

as pointed out above, I have found that lthis ,swinging or rotative movement is the most efcient method of penetrating the casing with a aisaoos of maximum inclination andthe the downward movementof the body from the position shown in Fig. 8 to penetrate the 'inner tool of this nature, As the cutter is swungby casing, it is gradually brought to the position' shown in Fig. 9 where an intermediate point on the shoe engages the second fulcrum point or cam face 2 I. The tool is preferably constructed so that this position is reached just at the time when the point of the blade engages the outer casing i2.

It will now be seen from the position shown Fig. 9 that the line of thrust has moved to the position L'V since the blade is now being swung about the second fulcrum point 2l, and the proportions of the tool are preferably such that the angle which this second line of thrustL' makes with the second casing is also in the neighborhood of 65. In the particular position shown,

, where the cutter has'moved a slight distance 46 indicate stop about this fulcrum, the angle B is substantially 70. As the tool is forced downwardly from the position shown in Fig. 9, the blade is swung so as to penetrate the outer casing and when this pene tration has been completed the cutter assumes a position as shown in Fig. l0 where the flanges 33. 33' come into alignment with the guide ways of the T portion i3 ofthe inclined section Il in the slot. In this position the blade assumes what I may term the angle of maximum extension.'

In other Words, the resultant line of thrust is substantially perpendicular to the surface or area which is being pierced. During the continued downward-movement of the body, the blade is held against further swinging movementor rota-z tion by virtue of the' engagement of the shoe portion or iianges V33, 33' in the guide ways i8 and. the blade is simply pushed forward along a straight line by engagement of the back of the shoe with the inclined face in the rear of the l slot.

f Fig. ll illustrates the blade as having been pushed forward a substantial distance beyond the point shown in Fig. 10, and it will be understood that the tool will be driven down until the maximumipenetration is obtained when the cutter is engaged by the block 31. At this point, the shoulders 35 will have been brought into engagen ment with the periphery of the perforation. The cutter is withdrawn oy merely lifting the tool, since the blade is held against upward movement by its engagement with the perforation, the guideways in the inclined slot drawing the cutter rearwardly as the tool is raised. The tool may be lifted a predetermined amount. and by again applying a downward driving force to the body. a new perforation can be formed. This procedurer may be carried on to any desired extent until the required perforated area is obtained.

The lock on the `mandrel has the advantage of permitting the tool to be lowered into the well again from the position of the uppermost perforation to place another row of perforations. This is accomplished by applying pressure to the body and rotating the tool to the left whichl brings the pin 45 into alignment with the notches 44 and 44', thereby permitting the mandrel and wedge block'23 to drop which permits the cutter vto fall into a completely retracted position in the socket. This permits placing as many rows of perforations as desired without pulling the` tool from the well for resetting the wedge block.'

It is to be understood that. while I have herein described and illustrated one preferred form of.

my invention, the invention is not limited to the precise construction described above but includes within its scope whatever changes fairly come within the spirit of the appended claims.

I claim as my invention: i

1. A casing perforator comprisingtan elongated body having an inclined slot; a cutter mounted in said body for free sliding movement in said slot; a blade on said cutter adapted to be projected through said slot for perforating a casing; xed fulcrum means in the bottom portion of said slot for rocking said cutter during the initial downward movement of said body while said blade engages a casing, said, fulcrum means comprising a concave surface on the body engaging the cutter; additional means for holding `said cutter against rocking movement in said inclined slot during a continued downward movement of said body; and means for controlling said cutter whereby said blade is engaged with a casing to be perforated.

2. A casing perforator comprising: an elongated body having an inclined slot; a cutter mounted in said body for free sliding movement in said slot; a blade on said cutter adapted to be projected through said slot tor perforating a casing; xed fulcrum means in the bottom portion of said slot for rocking said cutter during the initial downward movement of said body while said blade engages a casing, said means comprising a concave surface on the body pivotally engaging the cutter; additional means for holding said cutter against rocking movement in said inclined slot during a continued downward movement of said body; and means for controlling said cutter to engage said blade with a casingto be perforated, said last mentioned means comprising a wedge member slidably mounted in said slot below said cutter, a mandrel attached to said wedge member and extending below said body, and friction means on said mandrel engaging the interior of said casing.

3. A casing perforator comprising: an elongated body having an inclined slot; a cutter mounted in said body for free sliding movement in said slot; a blade on said cutter adapted to be projected through said slot for perforating a casing; means in said slot for rocking said cutter during the initial downward movement of said body while said blade engages a casing;` additional means for holding said cut-ter against rocking movement during a continued downward movement of said body; a wedge block in said slot below said cutter for swinging said cutter to project said blade into engagement with a casing; a mandrel secured to said wedge block and extending downwardly below said body; a

pair oi spaced plate members slidably mounted` on said mandrel; spring members secured to said t plates for frictionally engaging said casing; pin

means extending transversely through said mandrel; slots in one of said plates for passing :aid pins; and stops on said slotted plate for engaging said pin to limit the rotation of said mandrel relative to said slot.

4. A casing perforator embodying: a body member; a cutter swingably mounted in said body member; to be projected from said body for perforating a casing: a pocket in said body for normally supporting said cutter in a retracted position; and

means for swinging said cutter into engagement with a casing to be perforated comprising a wedge block slidably and non-rotatably mounted in said body below said cutter, a mandrel secured at its upper end to said wedge block and extending downwardly below said body, a pair of spaced a blade on said cutter adapted plate members slidably mounted on said mandrel. springmeans secured at their ends to said plate members for frictionally engaging said casing; pin means extending transversely through Said mandrel, slots in one of said plate members for passing said pin means, and stops on said slotted plate member for engaging said pin means to limit the rotation of said mandrel relative to said slot after said pin means has been drawn therethrough.

5. A casing perforator embodying: a body having a slot; a cutter mounted in said body for free sliding movement in the slot therein; a blade on said cutter adapted to be projected from said slot Yinto engagement with a casing; means in said slot for normally supporting said cutter in a retracted position; means for swinging said blade from said slot into biting engagement with said casing comprising fixed fulcrum means in said slot for rocking said blade to perforate said casing during an initial downward movement of said body, said fulcrum means comprising a concave face on the body cooperating with the cutter; and means comprising guide ways in said slot and iianges on said cutter for reception in said guideway for holding said blade against rocking movement and at the same time moving same transversely into an extended position during a continued downward movement of said body.

6. A casing perforator embodying: a body hav- I ing a slot; a cutter mounted in said body for free sliding movement in the slot therein; a blade on said cutter adapted to be projected from said slot into engagement with a casing; means in said slot yfor normally supporting said cutter in a re- I tracted position; iixed fulcrum means adapted to engage said cutter and impart a plurality of independent swinging movements to said cutter thereby rocking said blade to perforate a plurality of casings during an initial downward movement of said body. said fulcrum means including a concave face on the body cooperating with the cutter and a convex face on the body cooperating with the cutter; and means for holding said blade against further rocking movement and at the same time moving same transversely into an extended position during a continued downward movement of said body.

7. A casing perfor-atei' embodying: a body having a slot therein; a cutter mounted in said body 5 for free sliding movement in said slot; means for normally supporting said cutter in a retracted position in said slot; means for swinging said cutter to extend same into biting engagement with said casing including a plurality of fixed f fulcrums in said slot for `successively cooperating with said cutter to swing the same from an inclined toward'a horizontal position for perforating an engaged casing during an initial downward movement of said body, one of said fulcrums being a concave surface on the body for cooperating with the cutter: and means for holding said cutter against swinging movement and at the same time extending same transversely from said body during a continued downward movement of said body.

8. A casing perforator embodying: a body having a slot therein; a cutter mounted in said body for sliding movement in said slot; a blade on said cutter; fixed fulcrum means in said slot for swinging said cutter from an inclined toward a horizontal position during an initial downward movement of said body while said blade is engaged with a. casing whereby said casing is perforated, said fulcrum means comprising a concave surface of the body cooperating with the cutter; and means in said slot for holding said cutter against pivoting and at the same time forcing said blade from said body during,r a continued downward movement of said body.

9. In a casing perforator, a body having walls forming an inclined guideway, a concave xed fulcrum face in the guideway and a convex fixed fulcrum face in the guideway, a cutter member arranged in Asaid guideway and engaging the concave fulcrum face to receive free rocking movement during an initial downward movement of said body relative to said cutter. and engaging with the convex fuicrum face to receive a second rocking movement during continued downward movement of the body, and means on the cutter member engageable with said guideway immediately after said second movement for arresting the rocking movement of said cutter member and moving same through a substantiaiiy straight line into extended position during a continued downward movement of said body.

HAROLD C. YARBROUGH. 

